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Cricothyroid muscle

The cricothyroid muscle is a small, paired muscle of the larynx, crucial for tension and elongation of the vocal cords, directly influencing voice pitch. Located on the anterior surface of the larynx, it connects the cricoid and thyroid cartilages. Its unique oblique and straight fibers allow for precise modulation of the vocal folds, making it essential in phonation. Understanding its anatomy, function, and imaging characteristics is vital for clinicians dealing with voice, airway, and neck pathologies.

Synonyms

  • Anticus muscle

  • Tensor muscle of the vocal cord

  • External laryngeal muscle

Function

  • Acts as the primary tensor of the vocal cords

  • Tilts the thyroid cartilage forward on the cricoid cartilage

  • Elongates and tenses the vocal cords, raising the pitch of the voice

  • Essential for phonation (sound production)

Nerve Supply

  • Supplied by the external branch of the superior laryngeal nerve, a branch of the vagus nerve (cranial nerve X)

  • It is the only laryngeal muscle not supplied by the recurrent laryngeal nerve

Artery Supply

  • Superior thyroid artery (branch of the external carotid artery)

  • May also receive minor branches from the cricothyroid artery (branch of the superior thyroid artery)

Vein Supply

  • Superior thyroid vein

  • Drains into the internal jugular vein

MRI Appearance

  • T1-weighted images: Intermediate signal intensity, similar to adjacent skeletal muscle

  • T2-weighted images: Intermediate signal intensity, similar to adjacent skeletal muscle

  • STIR (Short Tau Inversion Recovery): Suppresses fat signal, so muscle appears intermediate to low signal; any pathology such as edema or inflammation within the cricothyroid muscle will appear hyperintense

CT Appearance

  • Cricothyroid muscle appears as a small, paired, soft-tissue density structure on either side of the midline, lying between the cricoid and thyroid cartilages

MRI images

Cricothyroid muscle MRI AXIAL IMAGE